Ultra processed has a largely unrecognised impact on behaviour and mental health.

In process: On food and mental health

Psychologist, author and former Bake Off finalist Kimberley Wilson tells Hugh Thomas of the unrecognised impact of processed food on our health and what to do about it.

As conventional wisdom suggests, eating nutritionally and avoiding processed foods lowers the risk of diabetes and other diseases, helps us maintain a healthy weight, and aids bodily functions like digestion. 

But that, it turns out, is only half the story. 

For the past decade or so, chartered psychologist Kimberley Wilson (who you may recognise from the Great British Bake Off Final in 2013, or her podcast work for BBC Radio 4) has called for a more holistic mind-and-body approach to nutrition. Meaning that, while eating healthily is of course good for the body, it is just as beneficial to our mental health. 

This could be game-changing. Reframing our perceptions towards nutrition in such a way can, for example, help us understand what someone’s relationship with food says about their depression, how different nutrients affect our personalities, and the extent to which processed foods are contributing to the mental health epidemic. 

It was about 12 years ago, while managing a mental healthcare service for inmates at HMP & YOI Holloway prison, that Wilson first made these kinds of connections. “A replication of a study had just come out,” she recalls, “which found that improving nutritional status in prisons could reduce objective incidents of violence by 30 per cent. 

Kimberley Wilson is a chartered psychologist and author of new book Unprocessed. Image Jesse John Jenkins.

“We don’t tend to think of your propensity for violence as being linked to diet, but the way that we eat, the quality of our nutrition, and our nutritional status can have profound effects on how we feel in ourselves, and also on our behaviours.”

Despite such eye-opening research, Wilson says access to nutrition-rich foods in prisons has generally got worse in the time since, largely because the media doesn’t deem it an interesting topic in which to investigate, but also because electoral candidates want to appear tough, rather than merciful, on perpetrators of crime. “That’s what sells and that’s what appeals to the base,” she says.

Wilson’s therapy work and research has taken her further across the public sector into hospitals and schools. In these institutions however, attitudes towards nutrition are unfortunately similar. 

We don’t tend to think of your propensity for violence as being linked to diet, but the way that we eat, the quality of our nutrition, and our nutritional status can have profound effects on how we feel in ourselves, and also on our behaviours.

“You can find some school lunchtime menus online,” says Wilson. “And what’s really striking is how they’re set up like takeaway services, or school versions of our high street chains. There’s a version of a Subway, a version of a pizza restaurant, and a version of a burger restaurant. And it’s almost priming young people to expect that this kind of fast food, convenience, ultra-processed way of eating is just the norm.”

This is particularly alarming given how important nutrition is to childrens’ learning and development. Current estimates are that, in the UK, more than half an adult’s calories come from ultra-processed foods (UPFs). Among children however, that figure is more like 65 cent, making them even more susceptible to mental – and physical – health issues. 

“We know rates of childhood mental health disorders, particularly among girls, have increased at their highest rate since record began in the last 15 to 20 years,” Wilson says. 

“When we look for reasons why, we often say that’s about the same time as we’ve had social media. I think social media can be quite detrimental to wellbeing and self-esteem, but it’s also the period of time when we’ve had a huge deluge of UPFs and those foods coming into schools and becoming much more affordable.”

More worrying still, for girls raised on a diet high in processed foods, then reaching child-bearing age, there risks a never ending spiral of nutrient-deficient mothers giving birth to nutrient-deficient children, stymying brain development and, ultimately, learning ability. 

“For example, when you supplement pregnant women with choline [which also naturally occurs in food such as eggs, beef liver, and fresh fish] during pregnancy, their children at ages 8 and 11 are much more able to concentrate and focus,” Wilson says. “In terms of academic achievement, concentration and focus is what’s linked with better academic outcomes.”

It emphasises how the link between nutrition and mental function is as yet unprocessed by society and, even, many health professionals. By no coincidence, Unprocessed is also the title of Wilson’s new book, which recognises that access to nutrition is partly a systemic issue, and rather than solely determining it the responsibility of the individual, instead providing evidence of the need to, as Wilson says, “incorporate the role of government food policy in improving long-term brain health and mental health in the UK.”

Given the nature of these challenges, Wilson recognises change must happen gradually, and that food produced sustainably – while important – is at the moment more of a “higher tier” concern. 

“For most people, we need to get them off an ultra-processed white loaf, even onto an ultra-processed wholemeal loaf,” she says. “At the moment, people just aren’t eating enough fruit and veg, and that’s kind of where I think we need to start.”

Unprocessed: How the Food We Eat is Fuelling our Mental Health Crisis by Kimberley Wilson (£22, Penguin) is out on 23 February.


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  1. All of us who read this need to work out, together, here, perhaps? how we CAN get this knowledge into the mainstream and politicians’ consciousness.
    In the constituency of Bolsover where I live, there isn’t even any sixth form available. Not to mention frequent invisible but choking clouds of toxic phenols arising from the ‘clean-up’ of the old Coalite chemical plant site close by M1 J29A. And people here have no idea about nutrition whatsoever. So much for ‘levelling up’!
    And the article doesn’t mention hospital food [maybe the book does] – don’t even get me started! Staff threw away fresh garden plums and other fruit [taken in by me to balance the incredibly deficient hospital food] from my husband’s bedside table while he slept 2 years ago.
    I am incredibly blessed to have been brought up by parents who had a science background and knew the importance of unprocessed foods and a proper balanced diet. A 2lb bag of sugar lasted many years as only ever used for tea for any workmen in the street!
    Now grandparents we still eat on a pattern of main meal= protein item, carb item, root veg, & green veg every meal. Fruit for ‘pud’, fresh or home-frozen. Our girls were very seldom ill. I talk to anyone I can to explain as simply as necessary things such as the effect of artificial fertiliser on the nutrient content of foods.
    It drives me potty that so many of the ‘supplements’ sold have eg zinc oxide and magnesium oxide ingredients, from which the gut cannot get much zinc or magnesium. Result; people find that supplements do little to help and so all supplements are discredited.

    Bright ideas welcome, come on, Wicked Leeks Community!

    1. Hi Denby,

      So many good points in here. We absolutely agree that there is such a need for nutrition to be prioritised within our institutions – schools, hospitals and many more. It sounds like your simple formula for creating meals is a winning one, and it’s wonderful to hear that you are spreading this message. Another vote here for intelligently formulated supplements with bioavailable nutrient forms too, a very good point. Lets all keep having these important conversations.


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